Defending Tour of California champion Tejay van Garderen will not race this year to concentrate on preparations for the Tour de France.

Riders will face the longest and most challenging stages, as well as the time trial, in the first three days of the race. The longest stage is 120 miles.

"It's likely we'll see a change in the overall leader up until the final day," said Kristin Bachochin, executive director of the race. "That definitely keeps everybody on their heels."

During the most difficult stage on Day 3, the cyclists will end a 108.5-mile ride by ascending 10.8 miles up Mt. Diablo.

The winner could remain unclear even until the last day of the race, when riders will have to face short and steep climbs in Thousand Oaks that could allow cyclists more adept at climbing hills to break away near the end of the race.

"It's going to make it tough for whoever is defending the jersey," Wiggins said. "It's going to go right down to the wire."

This year's event will include two days of women's racing — the most in the race's history. On the first day 115 riders will compete in a 125-mile circuit race. On Monday, a smaller field of riders will compete in a time trial in Folsom.